Lille (France) (AFP) - It's taken him 16 years as a pro, but Roger Federer finally has won all there is to win in tennis -- well almost.All four Grand Slam titles -- a record 17 in total -- six ATP year-end titles, 23 Masters Series, Olympic gold and now the Davis Cup for Switzerland.The Olympic title of course was in the doubles with Stan Wawrinka in Beijing in 2008 and he has yet to match great rival Rafael Nadal and Andre Agassi as the only men to have won all four Grand Slam titles, Olympic singles gold and the Davis Cup during the course of their careers.But still -- it's an astonishing record for a player many consider to be the greatest of all time.The Davis Cup win was arguably the hardest of them all for Federer to win, involving as it does other players and doubles action.Asked to compare his feelings in winning Wimbledon for the first time in 2003 and what he felt on Sunday after supplying the point Switzerland needed to win the Davis Cup final over France he replied: "You can't compare."When I won Wimbledon, it was a total shock, honestly. Davis Cup is something that I knew was possible at some stage in my career."Of course, there was the pressure of being able to manage all this and make everyone happy with all the support we had for the team and everything.So it is a totally different feeling."Also I was not alone on the court. This changes totally everything."Federer's first tournament as a professional was in the Swiss ski resort of Gstaad in 1998, where he lost in the round of 32.Although rated as one of best juniors in the world, there was no real hint at that time what tennis was about to witness as he entered the professional sphereIt wasn't until he defeated Pete Sampras at Wimbledon in a fourth round match in five sets in 2001 that his true potential became clearer to see.Still, he struggled to make much headway in the Grand Slam events and question marks were raised when he lost miserably to Luis Horna in the first round of the French Open in 2003.Federer came up alongside a generation of young champions who achieved immediate success, like Lleyton Hewitt, Andy Roddick and Marat Safin.While his contemporaries were shooting up the rankings and winning Grand Slam titles, he struggled to break through.- Days of frustration -"I don't want to say I was frustrated, but I didn't understand why it wasn't happening for me," Federer said last year. "I was far enough behind that I was, 'OK, let's push myself a little more'."A month after his Paris flop, that change of attitude reaped immediate dividends as Federer produced a majestic display over the Wimbledon fortnight, defeating Mark Philippoussis in straight sets in the final.The Federer era had begun in earnest and he dominated tennis over the next four years winning 10 Grand Slam titles. On two occasions -- in 2004 and 2007 -- he won three out of four.By that time Spanish claycourt king Rafael Nadal had come along to become the player Federer has always seen as his greatest rival.Nadal ruled at Roland Garros and it took his shock defeat at the hands of Robin Soderling in 2009 to clear the way for Federer to finally win the French Open, thus completing the Grand Slam set.By that time he had won Olympic gold with Wawrinka in 2008 and by Wimbledon 2012 he had taken his haul of Grand Slam titles to an all-time best of 17.Still the Davis Cup remained out of his grasp and, at 33, time was clearly running out when he and Wawrinka decided, after the latter won the Australian Open at the start of the year, that they would commit totally to playing the Davis Cup this year.They swept past a Novak Djokovic-less Serbia in the first round, edged a nervy outing against Kazakhstan in the quarter-finals and comfortably saw off Italy in the semis.France away in the final was a different prospect, however, with players of the calibre of Jo-Wilfried Tsonga and Gael Monfils on the other side of the net.A fractious match against Wawrinka in the semi-finals of the ATP World Tour Finals when the two argued and Federer damaged his back did not help.But all that was swept aside in Lille as Switzerland became just the 14th country to win the Davis Cup."For me personally, obviously I'm unbelievably happy because I've been playing in this competition for probably almost 15 years now," he said."At the end of the day I wanted it more for the guys and for (coach) Severin (Luthi) and Stan, the staff and everybody involved.This is one for the boys."Join the conversation about this story Click here to read full news..